Levels of selection are different for prey for whom the interaction is life or death and predators for whom the interaction is only a dinner or not.
What is predation?
Consumption of one organisms or part of the organism while the prey is still alive (thus excludes detritovores). 3 types are carnivory, herbivory and parasitism.
(Carnivorous) Predator Adaptions
need to be successful enough to survive and reproduce. Have from and function adaptions to help with their diet (teeth, digestive system) and sense adaptions to help them locate prey and stay safe. Additionally they have behavioral hunting adaptions (ambush, foraging and cooperative hunting)
(Carnivorous) Prey adaptions
Step 1 Avoid detection- being cryptic mostly visual. Step 2 avoid capture- getting away after detection through large fleets, alarm calls, startling predators or flash targets. Finally Step 3 disrupt predator handling- defensive weapons, chemical deterrents, spines, aposematism.
(Herbivore) Predator Adaptions
Different types. Grazers- leafy material, browsers- woody material & bark, granivore- plant seeds, and frugivore- fruit. Some migrate or hibernative as plant quality changes. sequestering or detoxification of plant toxins. behavior- eat the less toxic parts. longer digestive track for more absorption.
What is the main type of plant defense & why?
defense mechanisms not hiding or running because they can’t really. their complex & highly prevalent defenses is evidence of the strong selective force of herbivory.
(Herbivore) Prey adaptions aka plant adaptions
biochemical through toxin repellents & secondary compounds. Structural- low nutritional content of plant tissues (build up silica), spines, hairs, resin, tough seed coat.
associate only with a few hosts during its lifetime to obtain nutrients in stable environments. found in every almost every phylum. Life style traits: external or internal, survival of host detection & defenses, much smaller than host, dispersal through hostile environments and often complicated life cycles with multiple hosts.
predicts effects of predation on pop. growth. ** FLASH CARD***
Prey population is a density dependent regulator or predator population
per ca pita rate of predation increases linearly with number of prey.
When can the Lotka-Voltera model predict changes in predator population
when deaths of a predator are constant and births of the predator depend upon prey density.
Limits to Lotka-Voltera Model
sometimes rates of prey capture inscreases with increasing density. predator keeps consuming no matter how many prey consumed. doesn’t count for refuges-places where prey hide. co-evolution of predator and prey. increasing difficulty of in finding prey as it becomes scarce.
Interactions among populations with in the same space & time. Consists of many species interacting in many ways.
Two main: abundance & diversity. also includes physical appearance of pops (size & distribution_ and niche structure (# of niches, how niches compare & interact.)
guild vs lifeform
group of organisms that make their living in a similar way (animals.) vs same def for plants.
Number of individuals in each species. measure through counting, sampling or mark-recapture.
Mark-recapture assumption & downfalls.
Assume: population stays constant, tags are not lost, animals are not effected & that enough time has pass that tagged animals are mixed throughout the pop. Downfalls: birth, deaths, immigrations & such. additionally many species become elusive after being captured once.
Peterson method of mark-recapture
N= (MC)/R where N is population estimate. M is total number marked. C is total caught on second capture. R is number on recapture that were marked.
Importance of diversity
characterizes a community, explains patterns of biodiversity, allows diversity comparisons among communities, allows investigation of influence of diversity on communities * monitor of diversity over time.
D=N max/ N where N max is total number of most common species and N is number of species in the community. (incorporates abundance.)
Hs(actual diversity)/H max (max diversity possible). Where 0 is the most uneven and 1 is completely even.
Importance measures for diversity
richness, evenness, uncertainty, abundance.
McArthur & warblers
Studies warblers and the complexity of environments vs diversity of communities.
used to directly compare diversity between communities. example Jaccard
What influences/drives the diversity of communities?
lots of theories. The niche theory says that the complexity of an ecosystem/number of niches possible increases diversity of that community.
diversity of mammals & birds?
Mammals more diverse near the tropics while birds are more diverse near the arctic.
What influences community structure?
Equilibrium Theory of Community Structure vs Non-equilibrium Theory of Community Structure.
Equilibrium Theory of Community Structure
certain forces & processes (competition, predation, exclusion, ect.) organize communities. processes reach equilibrium. communities are thus highly organize and structure reflects years of interactions.
Non-equilibrium Theory of Community Structure
communities are constantly changing & environments are dynamic. disturbance & its affects are more important in determining structure. all species are responding to their environments over the long time. not highly organize, but a random assemblage of species individual responding to environmental changes. equilibrium is not reached.
Determinants of Species Diversity Top 3
1. Latitude which affects temperature (more important for terrestrial. 2. Depth which affects temperature (more important for aquatic). 3. Pollution.
Diversity & latitude
highest diversity in tropical areas which decreases to lowest as it moves to poles.
Diversity & depth
tends to increase to approximately 2000 m & then decline below that. yet diversity of the deep-sea has at times been found to be surprisingly high.
Diversity & pollution
diversity & abundance decline as pollution increases.
6 explanations for communities with high diversity
1. structural heterogeneity- more structurally diverse systems tend to be more species diverse. 2. ecological time- high diversity communities have been stable long enough for immigration to increase diversity. 3. Evolutionary time- high diversity communities have simple been in existence long and have had more opportunities for evolution. 4. climactic stability- leads to increased diversity through more time to specialize & less extinctions. 5. Primary production- positive correlation between primary production and species diversity.
Island Biogeography ** LOOK at GRAPHS**
islands tend to have low species diversity. Larger islands have more. As do islands closer to mainlands. Diversity results mainly from immigration rates vs extinction rates. these rates are affected largely by island size and distance from mainland.
Diversity can lead to community stability
In a complex web one species is generally less important than in a simpler system (* does not apply to keystone species)
What is stability
defined by two main terms. Resistance- ability to resist perturbation vs resilience- ability to return to normal after a disturbance.
Food Chain knowledge
Most species are involved in numerous interactions. Since tropic levels are based on function species may thus be in multiple trophic levels.
Food web generalizations
As the number of species in a web increases the number of links among them does too. as you increase the trophic level organisms tend to get bigger. there is a limit to the length and number of links. proportion of predators to intermediates to producers is relatively constant among communities.
limits to food chain length
limited by efficiency of energy transfer. longer chains are not stable- top predator more likely to become extinct.
dry weight of all organic matter contained in organisms within an ecosystem or within a specific trophic level. often measured by weight/productivity (g/m2/yr).
2nd law of thermodynamics
with each transfer of material between trophic levels some energy is lost.
% of energy transferred from one trophic level to the next. about 10% usually. thus 90% of biomass/productivity is lost with each level.
Primary productivity and it’s importance
the process where by primary producers capture light energy and transform it into chemical energy in bonds of carbohydrates. key in bring energy into the system and sets up the limit for all trophic levels above it.
gross primary production
total energy assimilated
net primary production
energy accumulated by the producer (has the loss of respiration which is the energy consumed by the producer).* Is what is available for the next trophic level.
Limits to primary production 4
Light- not usually limiting except in shade & water. only 1-2% of sunlight is harvested. Temperature- important, productivity increases with temp but so does respiration, optimum varies among communities. Water- the limiting factor for terrestrial ecosystems. Nutrients- the limiting factor for aquatic ecosystems (esp. P) . nutrients also limit terrestrial systems (esp. N).
Variations in primary production
terrestrial: highest in tropics, wetlands, marshes swamps lowest in tundras & deserts. Aquatic: highest in upwelling & continental shelves, kelp beds, coral reefs & estuaries. Low in the open oceans.
How much primary productivity do humans use?
40% of terrestrial primary productivity. 27% of earth’s potential.
I-Ingestion(energy content in food).F-egestion(energy content of indigestible feces). U-excretion(energy content of metabolic wastes-urine).R-Respiration(metabolism/energy consumed for maintenance).P-production (energy for growth and reproduction). Where I=F+U+R+P
ingested – egested (I-F)
Ingested – (egested+ excreted) I-(F+U)
assimilated energy- Respiration. I- (F+U+R)
assimilation/ingestion. how much ingested food energy is usable. seed eaters 80%, grazers 30-40, animal foods 60-90, decaying wood- 15.
net production efficiency
production/assimilation. how much usable energy goes towards growth, rest goes to metabolic activity. birds and mammals very small amount. cold-blooded is about 75%.
gross production efficiency
production/ingestion. how much ingested energy goes towards growth. birds & mammals 1%, aquatic up to 30%, avg 10-20%.
Production efficiency in plants
different than animals. net production/gross production. varies between 30-85. temperate is 75-85 vs tropic-s 40-60.
gradual change in species composition of a given area due to changing environmental conditions. a characteristic of all communities!
gradual establishment of biotic communities are nearly lifeless ground/ virgin ground. (no soil or sediment). Terrestrial-usually takes a long time. pioneer species arrive & build up soil. mid sucessional species arrive that are less hardy and need more nutrients & water. then shading creates platform of late succession plants.
arrive at newly formed habitat. lichens & moss -> start soil formation.
mid succession species
small grasses, ferns & herbs. grow close to ground, r-selected, short-life span, establish quickly.
reestablishment of biotic communities in an area where natural community has been disturbed, removed or destroyed. still has soil or bottom sediment. (includes polluted areas)
species diversity, niches, energy flow & efficiency, trophic structure & nutrient cycling.
Role of colonizers in succession
Facilitation, inhibition, tolerance.
one set of species makes area suitable for species with different niche requirements aka lichens building up soil or shrubs creating shade.
early species hinder establishment & growth of other species. aka when plants release toxins to reduce competition.
late sucessional plants are largely unaffected by plant at earlier stages- they are tolerant of those conditions.
change in environmental conditions that disrupt a community. may be catastrophic or gradual.
upsides to disturbances
create new conditions for new species and areas with intermediate disturbance(fairly frequent but moderate) have the highest species diversity.
Classic view of succession
occurs until area is occupied by a predictable and stable climax community. dominated by a few, long-live plant species. in balance with the environment, often called equilibrium model of community.
Alternative view of succession
continuous change, instability and unpredictability. community has an every changing collection of vegetation at different stages of succession. small and medium disturbances common and unpredictable. called the non-equilibrium model of community. struggle of individual species for survival. “mature” rather than climax community.
between organisms- photosynthesis and chemical respiration. between oceans and atmosphere- dissolving to HCO3- and CaCO3 sediments. Geological processes- CaCO3 sediments -> rocks. fossil fuels =/.
5 processes. Nitrogen fixation- N2 to NH3. nitrification- NH3 to NO3-. assimilation- inorganic N > plants > organic N. ammonification. organic N to NH3, recycled. dentirificition- NH3 to N2. human perturbations in artificial creation.
Nitrogen processes extras
Nitrogen fixation very specialized. Nitrification in aerobic conditions. denitrification in anaerobic conditions.
often very limiting. only slightly soluble in water and only readily available in soils between pH 6 -7. must be in PhO4^3- form to be assimilated by plants. human perturbations in mining and fertilizer runoff.
assimilated as sulfate. human perturbations in acid rain.
every habitat represents a different chemical environment
presence/absence of O2, energy sources, limiting nutrients.
Terrestrial nutrient regeneration
mostly aerobic. production limited by regeneration of nutrients from soil. Weathering & Detritus formation. climate influences & mycorrhizae are important!
Aquatic nutrient regeneration
most often anerobic in sediments & sometimes aerobic in water column. nutrients cycled from deeper water, dependent on upwelling. regeneration is quite slow. sedimentation general reflects the continuous drain of water nutrients.
More than 90% of plant biomass enters the detritus pool. quality varies depending on the type of plants, fungi present, climate(influences regeneration and rate). good detritus=productive soil.
Temperate vs tropical soils
slowly released supply of minerals from decomposition of organic matter. deeply weathered soil with little clay or ability to retain nutrients, rapid regeneration from detritus & uptake by plants & retention by organisms.
Regeneration in lakes and estuaries
lakes: often shallow enough for rapid regeneration or at least seasonal turnover. estuaries: rapid and local regeneration of nutrients. external loading of nutrients and exporting of much production =).
categories that group terrestrial ecosystems and communities by dominant plant forms. adjacent biomes overlap. help understand large scale processes and climate zones.
Biomes match environment
vegetation varies with the environment = biome. no single pants endures the entire range of conditions on earth. physical environment and climate limits plant distributions and biomes.
Influences on plant distribution
climate, physical environment, geographic features, interactions with other organisms, chance & history of colonization and catastrophic events, adaptions of organisms & tolerance levels.
single most important climate factor defining biomes?
Climate zone boundaries
based on temperature and annual course of water. 9 zones from pole -> equator.
warm-moist, warm-dry, cool-dry, cool-moist (too extreme for plants).
Tropical Climate zone
3 Biomes exists with hot-wet and hot-dry extremes. close to equator. temperature fluctuate more daily than annually.
Temperate Climate zone
5 Biomes exist with wet and dry extremes & moderate temps. moderate climates. limited by growing season and water. vegetation dominated by deciduous trees with understory of small trees, shrubs & herbs.
Polar Climate zone
1 Biome exists with a cold & dry extreme Avg. temp below 5*C. Boreal forest- btween 5*C and -5*C. Tundra- below -5*C.
heterogeneous area consisting of distinctive patches organized into a mosaic pattern.
the study of relationships between spatial patterns & ecological processes over a range of scales. principle feature includes changes in landscapes and the resultant influences of changes on organisms.
3 facets of landscape ecology
interdisciplinary- including natural & social sciences & humanities. Human influences- greatly affect landscapes!. Ecological consequences of spatial patterns- extent, origin, and effects across multiple spatial scales.
size, shape and composition, number and position of habitat patches or land scape element. major influence for the organisms inhabitanting the landscape.
Structure at different scales
individuals structure influences their role, population structure results from ecological influences, community structure influenced by interactions and landscape structure influences organisms inhabiting the area.
patch- relatively homogeneous area that different from its surroundings. form a mosaic that makes up landscape structure. vary in size, shape, number and composition and distributed on a variety of spatial patterns. vs Matrix- background mosaic upon which patches are formed, made by the most dominant vegetation.
Major Landscape changes
Fragmentation- often occurs as a result of humans. edge affects- as a result of fragmentation. may increase diversity and decrease habitat quality. corridors- link patches within a matrix & are important for migration, immigration and dispersal.
the physical and biological transitions from one ecosystem type to another. also called ecotones. edges have species common to both areas and unique species -> high diversity. sadly edges also cause drier, winder, weedy, parasitic and vulnerability to predators.
flow of energy & nutrients & species among patches. dispersal of species, extinctions, population changes and water fluxes.
Geographic Ecology what we need to know
species richness, island biogeography, influences of species richness.r
4 reasons to value biodiversity
Moral responsibility to be stewards of the earth, benefits to humanity, communities/ecosystems provide essential services, biodiversity maintains optimal community.
biodiversity and uncertainty
we are no good at telling useful and useless. we have only investigated 5% of organisms for potential medical properties. we should preserve what we don’t fully understand.
25 hotspots contain 35-45% of endemic species and occupy 1.5% of the land.
Factors and Causes of extinction
Humans over 300 times the background rate. 1 per day instead of 1 per year. until 1950s it was mostly from over-exploitation now it is mostly habitat destruction & fragmentation expect in the oceans. small population sizes & invasives also contribute to extinctions.
International Union for the Conservation of Nature.
ESA Endangered vs threatened species
endangered- organisms in danger of extinction throughout all or a significant part of its range. threatened- organisms likely to become endangered throughout all or a significant part of its range within the forseeable future.